1. Field of the Disclosure
The present disclosure broadly relates to the provision and use of videometry in various operations relating to the field of oil-well drilling, particularly offshore drilling operations. The disclosure is particularly concerned with the operation of cranes to lift cargo from marine vessels.
2. Background of the Technology
Videometry may take various forms but can generally be considered to relate to the use of optical sensing devices to automatically receive and interpret an image of a real scene, to obtain geometrical information, and to control directional information, the location or orientation of a component part, or simply the presence or absence of an object or component in a particular environment.
Crane operations are considered to be one of the most dangerous operations on a modern offshore drilling platform. Every offshore crane is configured and dimensioned to be able to lift a given load at a maximum hoisting speed for a range of lifting radii through which the crane may operate. If the load is too heavy, there are two possible failure scenarios which may occur.
The first of these failures is break down of the crane. This is normally not a significant problem, because the weight of each load is usually known and the operating radius of the crane can be well controlled so as to remain within safe limits for a given load.
The second type of failure is a so-called “re-entry” failure and occurs if the load is not lifted from the supply vessel sufficiently quickly as the vessel heaves, rolls and pitches in the sea below the crane. In such a situation, the load and the vessel may impact with one another after the load has been initially lifted from the vessel and before the load is lifted sufficiently clear of the vessel. This can damage the load and may jeopardise the safety of the vessel, its crew and the structure of the crane itself due to shock loads transmitted through the lifting cable.